Is the £1,000 trading allowance per platform?

No. The trading allowance is £1,000 per person, per tax year, across all your trading. Selling £700 on Vinted and £600 on Depop isn't two amounts under £1,000. It's £1,300 of trading income, which is over the allowance.

GOV.UK talks about your gross trading income "from one or more trades". It also covers other trading income, such as casual services like babysitting or gardening. (GOV.UK: trading allowance)

Why this catches people out

Each platform reports you separately, and only once you pass its own limit of 30 sales or about £1,700 in a calendar year. You could stay under the reporting limit on every app and still be over £1,000 in total. Being under the reporting limit isn't the same as being under the allowance.

What to do if you're over £1,000 in total

• Register for Self Assessment if you haven't already.
• Add up your sales across every platform for the tax year (6 April to 5 April).
• Deduct either £1,000 or your real costs: what you paid for the items, fees, packaging and postage you paid. Use whichever leaves you less profit.

Combine your platforms

The reseller tax check reads Depop and eBay sales files, or any CSV, and lets you type in Vinted totals. Pro combines several platforms into one figure for each tax year.